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Basis for original (SCP) IDLH: ACGIH [1971] reported that the TLV for this chemical is believed to be sufficiently low to minimize the number of persons who become sensitized, but the limit is not low enough to prevent exacerbation of asthma in those already sensitized to p-phenylene diamine. Because sensitized workers may be endangered by concentrations far below the TLV, this cannot be used to set an IDLH. Therefore, in the absence of other toxicological data and noting that Patty [1963] reported systemic poisoning from industrial exposure to be unknown [Reichel 1934], for this draft technical standard the respirators have been selected on the basis of the assigned protection factor afforded by each device up to the saturated concentration at 20°C (approximately 29.1 mg/m3) rounded down to 25 mg/m3; only the "most protective" respirators are permitted for use in concentrations exceeding 25 mg/m3.

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA:

Lethal dose data:

Species

Reference

Route

LD50 (mg/kg)

LDLo (mg/kg)

Adjusted LD

Derived value

Rat

Rabbit

Cat

Rat

G. pig

Burnett et al. 1977

Hanzlik 1923

Hanzlik 1923

Lloyd et al. 1977

Sheftel 1988

oral

oral

oral

oral

oral

80

-----

-----

98

145

-----

250

100

-----

-----

560 mg/m3

1,750 mg/m3

700 mg/m3

686 mg/m3

1,015 mg/m3

56 mg/m3

175 mg/m3

70 mg/m3

69 mg/m3

102 mg/m3

Human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 25 mg/m3

Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for p-phenylene diamine. Therefore, based on health considerations and acute oral toxicity data in animals [Burnett et al. 1977; Hanzlik 1923; Lloyd et al. 1977], a value of about 50 mg/m3 would have been appropriate. However, the revised IDLH for p-phenylene diamine is 25 mg/m3 based on the concentration recommended originally in the Standards Completion Program for deciding when the "most protective" respirators should be used. Because sensitized workers may be affected by concentrations far below occupational exposure limits, exacerbation of asthma cannot be used to set an IDLH.